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Biomedical subjects

R Gil

Publications and source records attributed to R Gil.

At least 145 records · Page 8Linked to original sources
PubMed1991

RCS1, a gene involved in controlling cell size in Saccharomyces cerevisiae.

Cloning and sequencing of RCS1, Saccharomyces cerevisiae gene whose product seems to be involved in timing the budding event of the cell cycle, is described. A haploid strain in which the 3'-terminal region of the chromosomal copy of the gene has been disrupted produces cells that are, on average, twice the size of cells of the parental strain. The critical size for budding in the mutant is similarly increased, and the disruption mutation is dominant in a diploid heterozygous for the RCS1 gene. Spores from this diploid have a reduced ability to germinate, the effect being more pronounced in the spores carrying the disrupted copy of RCS1. However, disrupted cells recover from alpha-factor treatment equally as well as wild-type cells.

Amino Acid Sequence↗
PubMed1991

Cytogenetics, flow cytometry, cytophotometry and morphometry of 22 cases of primary breast carcinoma. A comparative study.

Cytogenetic, flow cytometric, cytophotometric and morphometric analyses were performed on 22 previously untreated, primary solid breast carcinomas. Although the cell nuclei as the primary object of these studies were the same in all the tumors, distinct features were evaluated in each case to determine to what degree the results obtained by these techniques are comparable. From the cytogenetic viewpoint, six tumors had a modal number in the diploid range, seven were in the triploid range, and two in the tetraploid range; seven tumors had no modal number. These data correlate with the flow cytometry and cytophotometry results obtained, with DNA values slightly higher than their respective chromosomal modes. However, no correspondence between chromosomal modes and mean nuclear area was found. Chromosomal markers have been identified that particularly affect chromosomes 1 (p11, q21-qter), 11 and 16, although no common markers existed in all cases. Cytogenetics is the most sensitive technique, but the low yield (22 out of 140 tumors assayed) considerably restricts its value in any prospective breast cancer study.

Adult↗
PubMed1991

[Diurnal variations of the composition of cognitive evoked potentials].

Auditory evoked potentials are recorded in 12 subjects 4 times per day: 08 30, 11 30, 14 30 and 18 30. The daily variations of N1, P2, N2 and P3 are studied globally and according to the (morning- or evening) type of subjects. The latency of N2 decreases during the day; it possibly reflects variations in vigilance. The P3 amplitude varies according to the subject typology: for morning-type subjects, P3 is higher in the afternoon than in the morning, and for evening-type subjects, P3 decreases from morning to evening. These evolutions possibly reflect the effort in attention required by different tasks.

Adolescent↗
PubMed1991

[Significance of the blink reflex in the Wallenberg syndrome].

The blink reflex was studied in 38 cases with lateral medullary lesions (Wallenberg syndrome). Twenty-one blink reflexes were abnormal. The most common abnormality is an afferent delay in the late reflex on the side of the lesion with a normal early reflex. This abnormality is not pathognomonic of the Wallenberg syndrome. The physiopathogeny is discussed.

Adult↗
PubMed1991

Internalization pathway of C3b receptors in human neutrophils and its transmodulation by chemoattractant receptors stimulation.

On the surface of phagocytes, C3b receptors (CR1) bind C3b-coated particles and promote their ingestion after activation by appropriate stimuli such as lymphokines or the chemoattractant formyl methionyl leucyl phenylalanine (fMLP) and fibronectin. The aims of the present study were 1) to define at the electron microscopic level the nature of the process responsible for CR1 internalization and 2) to dissect the mechanism by which a physiological activator (fMLP) stimulates this process. CR1 was visualized either by the immunogold technique or by quantitative electron microscopic autoradiography using a monoclonal anti-CR1 antibody. Both techniques revealed that after anti-CR1 binding, CR1 cluster on the neutrophil surface in a time-, temperature-, and antibody-dependent fashion, but do not concentrate in coated pits. CR1 internalization requires receptor cross-linking (does not occur in the presence of Fab fragments of anti-CR1) and intact microfilaments. It results in the association of the internalized material with large flattened vacuoles, organized in stacks. Together with the surface localization of CR1 close to cytoplasmic projections (ruffles), these observations suggest that uptake of CR1 occurs through a macropinocytotic process. Eventually, CR1 concentrate in lysosomal structures. fMLP markedly stimulates this pattern of CR1 internalization without affecting their clustering or their lack of association with coated pits. Stimulation by fMLP is inhibited by pertussis toxin, unaffected by preventing receptor-triggered cytosolic free calcium [Ca2+]i elevations, and mimicked by phorbol myristate acetate. Taken together our data demonstrate 1) that, in neutrophils, CR1 is internalized via a coated pit independent macropinocytotic process, dependent on intact microfilaments and receptor cross-linking; 2) that, in the same cells, fMLP is internalized via the classical coated pits pathway; and 3) that fMLP amplifies CR1 uptake possibly via protein kinase C stimulation.

Autoradiography↗
PubMed1991

Isolation and characterization of Saccharomyces cerevisiae mutants resistant to aculeacin A.

Aculeacin A is a lipopeptide that inhibits beta-glucan synthesis in yeasts. A number of Saccharomyces cerevisiae mutants resistant to this antibiotic were isolated, and four loci (ACR1, ACR2, ACR3, and ACR4) whose products are involved in the sensitivity to aculeacin A of yeast cells were defined. Mutants containing mutations in the four loci were also resistant to echinocandin B, another member of this lipopeptide family of antibiotics. In contrast, acr1, acr3, and acr4 mutants were resistant to papulacandin B (an antibiotic containing a disaccharide linked to two fatty acid chains that also inhibits beta-glucan synthesis), but acr2 mutants were susceptible to this antibiotic. This result defines common and specific steps in the entry and action of aculeacin A and papulacandin B. The analysis of double mutants revealed an epistatic effect of the acr2 mutation on the other three mutations. Cell walls of the four different mutants did not show significant alterations in composition with respect to the parental strain, and in vitro glucan synthase activity was also unaffected. However, cell surface hydrophobicity in three of the mutants was considerably decreased with respect to the parental strain.

Aminoglycosides↗
PubMed1991

[Evaluation of the activity of the heart conduction system with special reference to the sinoatrial node automatism in patients with mitral valve prolapse syndrome].

Electrophysiological examination of hearts were performed in 35 women and 25 men aged 18-63 years (mean age 38 years) without any concurrent heart diseases, divided into two groups: with PMVP (group I--40 subjects) and patients without this valvular anomaly (group II--20 subjects). In the patients with PMVP the examination revealed a significantly more frequent occurrence of the so-called "electrophysiological anomalies" (in 67.5%). The following appeared most frequently: sinus automatism disorders (32.5%), accessory a-v pathways (32.5%), longitudinal a-v node dissection (20%), and disorders of intracardiac conduction in segments: proximal (15%), distal (7.5%) and in both (5%). The implementation of pharmacological tests (with ajmalin, propranolol and atropine) made it possible to detect, in group with PMVP, the existence of occult conduction disturbances, particularly in distal segments of the conduction system (10%), and also to estimate exactly the character of the sinus node dysfunction (the background being in 7 patients functional, in 6 organic). During the programmed heart stimulation supraventricular dysrhythmias were evoked in 17 patients with PMVP. This is a proof that there is increased predisposition for paroxysmal supraventricular arrhythmias to occur in patients with mitral valve anomaly.

Action Potentials↗
PubMed1991

[Spontaneous bacterial pleuritis in 3 patients with liver cirrhosis].

We report 4 episodes of spontaneous bacterial pleuritis observed in 3 patients with liver cirrhosis complicated by ascites and pleural effusion. This infection mimics spontaneous bacterial peritonitis. Three episodes were successfully treated. Proposed pathogenesis, diagnostic methods and therapy are discussed.

Ascites↗
PubMed1991

[Bacteremic meningoencephalitis due to Listeria monocytogenes in an immunocompetent adult].

A 34 year old non pregnant, immunocompetent female developed severe meningoencephalitis. Bacteriologic studies established listeria monocytogenes as the causative organisms. This agent, previously limited to affect immunocompromised hosts, has recently been shown to be transmitted by the oral route to immunocompetent persons. This is the first report of such case in Chile.

Adult↗
PubMed1991

[Central neurologic forms of Waldenström's disease. Bing-Neel syndrome. 3 cases].

Three cases of central nervous system involvement in Waldenström's macroglobulinemia (Bing Neel's syndrome) are reported. Such cases are unusual and have a poor prognosis. One patient received chemotherapy including BCNU, cyclophosphamide, vincristine, melphalan and prednisolone, which was followed by a dramatic improvement. The pathogenesis of Bing Neel's syndrome is discussed.

Aged↗
PubMed1991

[45,X/46, XYnf/47, XYnfYnf/46, X, dic (Ynf) (q12) mosaicism in a female patient with gonadal dysgenesis and the stigmata of Turner's syndrome].

A 17-year-old girl was referred to us because of primary amenorrhea and features of Turner's Syndrome. The karyotype obtained from peripheral lymphocytes cultures was mos 45,X/46, XYnf/47, XYnfYnf/46, X, dic (Ynf) (q12). The karyotype of fibroblasts derived from cultures of both gonads was mos 45, X/46, XYnf/47, XYnfYnf. The Y chromosome was non-fluorescent in all the examined lines. We report here the clinical and cytogenetic findings in a patient with an unusual sex chromosome mosaicism.

Adolescent↗
PubMed1991

[Cognitive evoked potentials at the stages II and III of human immunodeficiency virus infection].

Neuropsychological and psychometric investigations have sometimes attested to and sometimes denied the existence of cognitive perturbations during the early phases of human immunodeficiency virus (HIV) infection (stages II and III of the CDC classification): strictly asymptomatic seropositivity or generalized lymphadenopathy. Therein lies the basis of the debate concerning the neurotropism of the virus and its deleterious effects on the central nervous system (CNS). We hoped to contribute to the resolution of this discussion by recording late evoked auditory potentials, which are composed of two types of components: exogenous responses attesting to the reception of stimuli by specific sensory areas of the CNS, regardless of their informative value for the subject; and endogenous responses that occur later, appearing when the subject is required to distinguish between different stimuli, for example, counting high-pitched sounds randomly distributed among low-pitched ones. The latter responses, which have been most extensively studied for wave P300, are associated with cognitive functions, and alterations of the evoked cognitive potentials have been observed during the course of demential syndromes of various origins. Fifteen individuals were subjected to the protocol for recording long-latency, evoked auditory potentials. These studies were completed by a battery of psychometric tests, two methods for evaluating depression and an assessment of the anxiety level. The results showed a significant lengthening of the latency of wave P300 in the seropositive subjects. This prolongation also affected one of the exogenous components, i.e., wave P2. In addition, their intelligence quotients, regardless of whether the IQ explores the so-called crystallized component or the fluid component of intelligence, were not significantly different from those of the general population.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1991

[The excitation-conduction system of the heart in primary mitral valve prolapse (electrophysiological study)].

Forty patients (mean age 40 yrs) with primary mitral valve prolapse (MVP) and 20 healthy controls were subjected to electrophysiologic investigation. The following measurements were performed: 1) intracardiac conduction time, 2) effective and functional refractory periods of the right atrium, a-v node and right ventricle, 3) Wenkebach point, 4) retrograde Wenkebach point. Disturbances of intracardiac conduction were detected in 13 (32.5%) patients with MVP (in 8 patients within proximal part of the conduction system, in 5 patients distally). Patients with MVP were more sensitive to ajmaline. Conduction time in the proximal part was significantly increased only in these patients. The incidence of retrograde conduction was more frequent in the patients with MVP than in the controls. In 12 (30%) patients with MVP, constant conduction time and high value of retrograde Wenkebach point were found. Mean values of effective and functional refractory periods of the right ventricle and effective refractory period of the a-v node were not significantly different in both groups. In patients with MVP, mean values of effective and functional refractory periods of the right atrium were significantly lower and functional refractory period of the a-v node significantly higher than in the controls. In 8 (20%) patients with MVP and in 2 (10%) controls, longitudinal division of the a-v node was found. Atrial hyperreactivity was detected in 14 (35%) patients and in 3 (15%) controls. In conclusion, MVP is often accompanied by electrophysiologic abnormalities, such as disturbed intracardiac conduction, retrograde preexcitation, shortening of atrial refractory periods, longitudinal division of the a-v node and atrial hyperreactivity.

Adolescent↗
PubMed1990

Human monoclonal IgM with autoantibody activity against two gangliosides (GM1 and GD1b) in a patient with motor neuron syndrome.

Small amounts of oligoclonal immunoglobulins were detected by Western blotting in the serum from a patient with motor neuron syndrome. The prominent one, a monoclonal IgM lambda, reacted strongly with the gangliosides GM1 and GD1b and more weakly with asialo GM1, as shown by immunoenzymatic staining of thin-layer chromatograms of gangliosides, ELISA on purified glycolipid coats and immunoadsorption with purified GM1. Affinity-chromatography with purified GM1 resulted in the purification of monoclonal IgM lambda. This purified IgM and its Fab fragments showed the same pattern of reactivity with gangliosides as that observed with whole serum. Such monoclonal IgM could be responsible for motor neuron diseases in some patients with overt or barely detectable monoclonal gammopathies.

Aged↗
PubMed1990

[Sinoatrial node in primary mitral valve prolapse (electrophysiological study)].

40 patients with MVP (mean age 36 years--group I) and 20 controls without any heart disease (mean age 40 years--group II) after thorough clinical examination (including Holter monitoring) were subjected to electrophysiological study for sinoatrial node function assessment. The following parameters were studied (before and after "pharmacological denervation"):, SNRT, CSNRT, SP and SACT (using direct method and Strauss and Narul's method). SN dysfunction was found in 19 patients with MVP (37.5%) and in 3 controls (15%) in 24-hour Holter ecg. In the electrophysiological study SN dysfunction was diagnosed in 13 patients (32.5%) of group I. 10 of them displayed also electrocardiographic symptoms of SN dysfunction. "Pharmacological denervation" of the heart (propranolol 0.1 mg/kg, atropine 0.02 mg/kg) revealed 4 cases of concealed SN dysfunction defining the functional background of abnormalities in 7 out of 13 patients. Our data show that SN dysfunction is common in patients with MVP. Electrophysiological study performed with "pharmacological denervation" may disclose cases of concealed SN dysfunction and define them as functional or organic.

Adult↗